This invention relates to methods for making fasteners of the type including two articles, at least one of which includes a field of headed projections adapted to releasably interengage with the other article, and in one aspect to methods for making such fasteners in which both articles include an array of headed projections which can be simultaneously engaged without regard to the relative angular relationship of the arrays.
The art is replete with descriptions of fasteners including two articles, at least one of which includes a field of headed projections. U.S. Pat. No. 3,138,841 describes such a fastener in which one article comprises a woven fabric backing from which extend a plurality of headed projections adapted to mate with loops of fiber projecting from another article. The projections on this article are provided by a plurality of flexible resilient monofilaments of longitudinally oriented polymeric material each including a central portion woven into the backing and end portions that form the projections. Such articles are produced by weaving two backing layers in parallel closely spaced relationship with the monofilaments being woven therebetween. The monofilaments are then severed midway between the backing layers to form two brush-like halves, and the newly severed projecting filaments are heated to form heads on their terminal ends. These articles, however, are expensive to make because of the weaving required, and the woven backing does not hold the monofilaments as tightly as may be desired. While the weaving process used precisely places the projections, it does not allow as much versatility as may be desired with regard to alternate positions for the projections of the backing, and thus would not allow them to be positioned in a pattern in which the projections on two such woven articles could most effectively interengage.
U.S. Pat. No. 3,527,001 teaches embedding projections of a longitudinally oriented polymeric material in a resinuous polymeric bonding layer and heading the projections so that they will releasably engage a low density fibrous cleaning disk. While fasteners including one article made by the flocking procedure taught in U.S. Pat. No. 3,527,001 might suitably engage another article of an open fibrous material, the flocking procedure taught is more time consuming and expensive than is desired for a low cost fastener article, and the positioning of projections on the headed article provided is too unpredictable to reliably produce two articles having headed projections that will effectively interengage.
The art also describes fasteners in which each of two articles do have a field of headed projections adapted to reliably and effectively interengage similar projections on the other article to releasably close the fastener. U.S. Pat. Nos. Re. 26,629; 3,266,113; 3,408,705; and 3,192,589 are illustrative. The articles described in these patents, however, also have certain disadvantages.
The heads of such articles must have clearance for movement past each other during engagement. The projections of some articles must be progressively engaged in the manner of engagement of the teeth of a zipper so that this clearance is provided on one side of the row of projections moving into engagement (see U.S. Pat. Nos. Re. 26,629 and 3,192,589). These articles require bending of their backings to allow their projections to sequentially engage or disengage which is normally not possible when the fasteners are used to attach two rigid members.
Other prior art articles have been specifically designed so that all of the headed projections on both articles can reliably be simultaneously moved past each other. This allows the articles to have a rigid backing or be fixed on a rigid surface, which is desirable for many applications. For such articles, however, clearance space must be provided within the pattern of projections. Two methods of providing such clearance space have been taught. U.S. Pat. No. 3,266,113 teaches deleting certain projections from an otherwise ordered array of projections to provide the clearance space needed for simultaneous movement of the heads past each other. Before the projections of this fastener will engage, however, the arrays in which they are disposed must be oriented in one of a limited number of predetermined angular relationships relative to each other. Such orientation of the arrays is inconvenient for many uses. U.S. Pat. No. 3,408,705 teaches providing the clearance space within an unordered array of projections which have minimum spacings from each other to allow engagement of the projections when the arrays in which they are disposed are oriented in any angular relationship relative to each other. While this fastener is more versatile, it like the articles of U.S. Pat. No. 3,266,113 is of a molded construction. Molding such articles is relatively expensive and produces projections which have less strength for a given diameter than do projections formed of the same material which is longitudinally oriented.